[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
Re: Ldap Servers sharing same mount point
Randy,
Trying with OpenLdap 2.0 seems to be the next step.
But, I may not be able to do that in a couple of
weeks, and may live with the partial-replication in
1.2.11.
ThanX for the detailed reply.
Santhosh
--- Randy Kunkee <kunkee@neosoft.com> wrote:
> >
> > When I modified gdbm_open function in the file
> > libraries/libldbm/ldbm.c to have GDBM_NOLOCK, I
> was
> > able to do ldapsearch from two LDAP servers
> sharing
> > the same NFS mount. But, doing a write from one
> LDAP
> > server and read from other one, caused the writing
> > LDAP server to crash. (So, this could not be
> > feasible).
> >
> > It seems, once the index file (dn2id.gdbm) is open
> by
> > the server, the lock acquired exists till the ldap
> > server is stopped. But, there should be no harm
> (I
> > mean none of the index/database files will be
> > corrupted) if only one slapd modifies the
> > database/processes the queries, while the other
> one is
> > only processing queries. I am not that an expert
> of
> > the OpenLdap source code, but any idea whether
> this is
> > feasible, if so how much time will it take ?
>
> Santhosh, you don't seem to appreciate the amount of
> trouble that
> you are headed for. You are trying to get slapd to
> do something
> it was definitely not designed to do. I would agree
> that multiple
> slapd processes could read the same directory if
> they are *all*
> read-only. To do what you are asking, you will need
> to put in
> code to detect changes to files so you can throw
> away old cached
> data. The options are, of course, endless -- you
> can do anything
> you want once you start programming, but I think
> your efforts would
> be better spent moving to 2.x, getting real
> referrals working, and
> working within the design of LDAP/slapd where you
> could get a lot
> more support from these lists.
>
> >
> > Are the index/database files modified during
> > ldapsearch ?
>
> They could be.
>
> > (My assumption is that they are modified only for
> > ldapmodify/ldapadd).
>
> But there is the potential (unless your particular
> setup avoids it)
> that a modify/add/etc. could occur at the same time
> (in another
> thread within slapd, or in the master slapd in your
> case) that
> the database could be modified while the search is
> in progress.
>
> >
> > I did not have any luck with slave slapd setup to
> get
> > data propagated to the master server.
>
> That's what the referral is for. While I understand
> there is work
> on LDUP (each server still has it's own copy of the
> database),
> which does more like what you are thinking, the LDAP
> way
> is to issue a referral to the client requesting the
> modify to tell
> it to go somewhere else to make the change. This
> keep replication
> simple.
>
> Another drawback of using a common directory through
> an NFS mount
> is that if you lose the system which is serving out
> the directory
> via NFS, you're down, period. One of the ideas of
> replicas is
> that a replica can stand on its own, at least for
> read-only operations.
>
> Randy
>
> >
> > I appreciate any help.
> >
> > ThanX
> > Santhosh
> >
> > --- "Christian J. Chuba" <cchuba@staff.mail.com>
> > wrote:
> > > Hugo, a slight clarification. We are only
> trying to
> > > use two slapd servers
> > > to 'read' the directory not update the
> directory.
> > > Are you saying that only
> > > one slapd server can access the same back end
> > > storage even for read
> > > operations?
> > >
> > > ----- Original Message -----
> > > From: <Hugo.van.der.Kooij@caiw.nl>
> > > To: "Iddyamadom Santhoshkumar"
> <iskumar@yahoo.com>
> > > Cc: <OpenLDAP-software@OpenLDAP.org>
> > > Sent: Sunday, December 03, 2000 5:59 AM
> > > Subject: Re: Ldap Servers sharing same mount
> point
> > >
> > >
> > > > On Sat, 2 Dec 2000, Iddyamadom Santhoshkumar
> > > wrote:
> > > >
> > > > > As part of setting up two ldap servers (for
> > > > > availability) we thought of setting up two
> > > machines
> > > > > with OpenLdap installed on both of them.
> Both
> > > "slapd"s
> > > > > point to the same database (same "directory"
> > > entry in
> > > > > slapd.conf in both machines). It is possible
> to
> > > do
> > > > > ldapsearch only on the machine where slapd
> is
> > > started
> > > > > first. On the other machine, ldapsearch
> gives
> > > > > "ldap_search: No Such object" . With
> detailed
> > > log, it
> > > > > seems the problem is ldbm_cache_open returns
> > > error 11,
> > > > > "Resource Temporarily Unavailable", while
> trying
> > > to
> > > > > open dn2id.gdbm
> > > >
> > > > I don't think you can have two servers
> accessing
> > > the same backend database
> > > > like this. Perhaps it works with a SQL backend
> > > database but it is a
> > > > nightmare setup.
> > > >
> > > > For multiple servers the replication daemon is
> the
> > > path to go.
> > > >
> > > > Hugo.
> > > >
> > > > --
> > > > Hugo van der Kooij; Oranje Nassaustraat 16;
> 3155
> > > VJ Maasland
> > > > hvdkooij@caiw.nl
> > > http://home.kabelfoon.nl/~hvdkooij/
> > > >
> > >
> >
>
--------------------------------------------------------------
> > > > This message has not been checked and may
> contain
> > > harmfull content.
> > > >
> > > >
> > > >
> > >
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! Shopping - Thousands of Stores. Millions of
> Products.
> > http://shopping.yahoo.com/
> >
>
__________________________________________________
Do You Yahoo!?
Yahoo! Shopping - Thousands of Stores. Millions of Products.
http://shopping.yahoo.com/